# builders.ac > API reference and guides for the sending.ac Mailbox API and Provisioning API. The Mailbox API sends and reads mail through an unmodified Microsoft Graph SDK. The Provisioning API white-labels mailbox provisioning and is in internal testing. llms-full.txt includes the full API reference. The raw OpenAPI documents are linked below and are the most precise description of either surface. ## Documentation Sets - [Abridged documentation](https://docs.builders.ac/llms-small.txt): a compact version of the documentation for builders.ac, with non-essential content removed - [Complete documentation](https://docs.builders.ac/llms-full.txt): the full documentation for builders.ac ## Notes - The complete documentation includes all content from the official documentation - The content is automatically generated from the same source as the official documentation ## Optional - [Mailbox API — OpenAPI 3.1 document](https://docs.builders.ac/specs/mailbox.json): Machine-readable spec for the Mailbox API. - [Provisioning API — OpenAPI 3.1 document](https://docs.builders.ac/specs/provisioning.json): Machine-readable spec for the Provisioning API.